Volcanoes and population

In 1985 I presented a population graph for Britain extending from the Mesolithic to recent times, which was characterised by periodic ups and downs, the lows being the result of catastrophic processes in which an overall loss of the order of 50% in a century was envisaged. This was on the level of the historical population disasters of the 6th and 14th centuries AD.

Just such a population collapse, I suggested should accompany the contraction and dislocation of settlement in the 12th century BC. What struck me immediately on reading Baillie’s 1988 account of his volcanic “events” was that so many of them matched, more or less, the ups and downs on my 1985 population graph. Here I offer some comments on their possible significance.

In radiocarbon terms the event of the 4370’s BC corresponds with the period around 3500 BC when the first Neolithic colonists arrived from the Continent; hence the rise in my curve. Recent fashion has been to play down the immigrant contribution to the British Neolithic, but someone has still to bring the sheep/goats and seedcorn; and medically, what would be the impact of outsiders from the Continent on an indigenous Mesolithic population which shows such scanty signs of having had any contact with the Continent since 6500 BC? The historical analogies suggest disaster for the indigenes.

One question which has received scant attention is why Britain and Ireland were only settled from c.3500 BC, when there were farming groups on the French and Dutch coasts for some centuries before this. Baillie’s “event” perhaps provides the catalyst, the final straw which launched the boats – not necessarily in vast numbers.

The event of the 3190s BC coincides neatly with the point around 2500 BC at which the Late Neolithic has for some time been divided from the earlier Neolithic. No more causewayed enclosures, long tombs and the like, and instead henges, passage tombs, Peterborough and Grooved wares, and all that goes with them. Just how a volcanically influenced climatic downturn could contribute to such changes I leave to others.

The answer presumably lies in knowing more about Neolithic settlement and agriculture. The match between “event” and fall on my graph should have been closer; my intention in 1985 was to dip the curve at a point equivalent to a calibrated date of c.2500 BC. I erred.

The event of the 1620s BC is the one that got away. I still cannot see any firm reflection of this in our Early Bronze Age record. There may have been a hiccup in the expansion of settlement in the marginal lands, especially the uplands, which had been gathering strength since cl800/1700 BC. A temporary setback or retreat would be very difficult to spot given the stratigraphic and artefactual exiguities of our upland sites. But when an economy is expanding, it can survive a disaster.

We have already discussed the event of the 1150s and 1140s; the next event is that of 207 BC. Somewhere about this point my graph begins to show the ever rising population curve which characterises the late Iron Age and Romano-British period. For long, Iron Age specialists saw the 3rd
century as a time of trouble, characterised by Marnian invaders and defence building and refurbishment; concepts which seem now to belong to another age. Yet in my own area, North-East England, there is good evidence for 3rd century attention to defence building; and by the 2nd century settlement had spread to marginal areas which had apparently been neglected for more than a millennium.

Colleagues may care to scrutinise their own regions with a 207 BC event in mind. This leaves the final event of the 540s AD. As Baillie himself has noted, the 540’s were a time of cold and plague. In particular this decade saw the pandemic of Justinian, with an effect on world population as catastrophic as the better known Black Death of the 1340s (see Russell, in Demography, 1968). That volcanic “events” could be linked both to contractions and expansions of settlement and population might seem like having one’s cake and eating it.

The explanation is perhaps that it depends on the level of population and settlement at the time. If there is room for manoeuvre, as in the 4370’s, 1620’s and c.207 BC, then settlement can be shifted and there is opportunity for expansion both of settlement and population. But if society is already at the margins, with nowhere else to go, as in the 12th century BC, then the volcanic “event” may well trigger complete collapse.

Colin Burgess

AcknowledgementsMy thanks to Mike Baillie and Victor Clube for answering my queries; to Peter Topping for his comments on this paper; and especially to DorisDavies, for coping with my scrawl.